CLASSIFICATION OF ACANTHOBDELLA
PHYLUM :- ANNELIDA (Metamerically segmented, coelomate and laterally symmetrical. )
CLASS :- HIRUDINEA (Annelids with fixed segments, without parapodia and with anterior and posterior
ORDER :- ACANTHOBDELLIDA (Antenor sucker, proboscis and jaws absent.)
FAMILY :- ACANTHOBDELLIDAE
GENUS :- Acanthobdella
Commonly present in West Siberia and N.E. Europe.
HABIT AND HABITAT
The order Acanthobdella includes a single genus Acanthobdella found as an ectoparasite on the caudal and anal fins of the salmon fish Salmo salvelinus
GENERAL CHARACTERSTICS OF ACANTHOBDELLA
- Body consists of about 20 metameric segments only.
- Anterior sucker is absent. Posterior sucker is well developed and consists of four segments.
- Each ventro-Iateral sides of first five segments contain 4 pairs of setae embedded in setigerous sacs provided with retractor muscles.
- Body cavity (perivisceral) is incompletely divided by 20 transverse septa.
- Visceral peritoneum consists of flat globules, containing cells corresponding to chloragogen cells.
- Nephridia with both external and internal openings.
- Blood vascular system made of a dorsal and a ventral vessel and nervous system consists of 20 ventral ganglia of which the first and the last are composite.
The external morphology strongly suggests that Acanthabdella is leech but Michaelson regarded it as oligochaeta due to setae and incomplete septa. However Acanthobdella represents good connecting link between earthworms and leeches.
Besides absence of anterior sucker, animal shows all above features, hence it is Acanthobdella.